This invention relates to radio frequency processing, and more particularly, this invention relates to radio frequency processing with phase lock looped circuits.
The use of wireless conductivity devices are becoming more commonplace in industry. For example, cellular networks are prevalent throughout the world. Also, wireless local area networks are becoming increasingly popular in certain areas. Many of these wireless applications use frequencies that exist within the frequency bands that do not require a site license from the Federal Communications Commission. An example of such a band exists at around 2.4 GHz, a licensed application space established by the FCC.
One wireless application space is a wireless cable replacement. For example, a wireless cable replacement would allow a computer keyboard to connect to a computer without the use of physical wires. It would be similar to an infrared application, but instead use radio frequencies, instead of light.
However, it is difficult to operate at the higher GHz frequencies using small monolithic circuits. The higher frequencies typically require separate chips and circuits. It would be desirable if a majority of a transceiver radio frequency processor could be incorporated monolithically and a simple design could be implemented that would allow a smaller number of components. This would be beneficial in the processing of intermediate frequencies that would be processed in such a system.
An apparatus for radio frequency processing includes a local oscillator synthesizer circuit having a voltage controlled oscillator that generates an oscillator signal f1. A divide-by-N circuit receives the oscillator circuit f1 and divides that signal to produce an f1/N oscillator signal. A dual modulus synthesizer is connected to the divide-by-N circuit and generates a quadrature modulus signal f1/N. A receiver circuit and a transmitter circuit are operatively connected to the local oscillator synthesizer circuit. Each of the receiver circuits and transmitter circuits has at least two mixer circuits for mixing and respectively down converting/up converting intermediate radio frequency signals. The local oscillator synthesizer provides local oscillation for each of the mixer circuits.
In still another aspect of the present invention, the receiver circuit includes a first mixer that receives the oscillator signal f1. The receiver circuit also includes a second quadrature function image reject mixer circuit that receives the f1/N oscillator signal and the quadrature modulus signal f1/N. A heterodyne mixer circuit receives the f1/N oscillator signal. The receiver circuit also includes a mixer that receives the oscillator signal from the local oscillator synthesizer.